1. Field of the Invention
The present invention relates to an absorbent article that absorbs body fluids, such as a disposable diaper, and particularly to an absorbent article with an indicator making it possible to visually ascertain whether an absorbent core in an absorbent article is wet.
2. Related Art
Conventionally, it has been known to provide an indicator in an absorbent article, such as a disposable diaper and a urine-absorbing pad, so that the excretion of urine can be ascertained from the outside of a liquid impermeable back sheet, namely from the outside when the absorbent article is worn. This indicator is positioned between the back sheet and an absorbent core of the absorbent article, and contains an indicating agent whose color shows clearly when wetting occurs.
For example, Japanese Unexamined Patent Publication No. H9-299401 discloses that an indicator includes an ink layer which shows clearly when wetting occurs and an ink covering layers which are interposed between the ink layer and a back sheet and are close contact with the ink layer, and that the ink covering layer contains a surface active agent.
On the other hand, Japanese Unexamined Patent Publication No. 2003-516185 discloses an absorbent article provided with an indicator that consists of an indicating agent whose color shows clearly when wetting occurs, and a base polymer. This absorbent article prevents the indicator from generating an error signal due to moisture, by employing a moisture permeable film as a back sheet.
In the indicator disclosed in the above publication No. 9-299401, a moisture absorbing paper is used as the ink covering layer, and the ink layer is formed by printing ink on this paper. The application of the indicator including this ink layer to a diaper may ruin its soft touch. Further, for the paper used in this ink layer, the absorbed urine is susceptible to diffusion into the paper. Therefore, when viewed from the outside of the back sheet, in some cases, the colored indicator may be blurred. If this is the case, it is difficult to distinguish the wet region of the absorbent core by using the indicator. Further in some cases, the ink of the indicator may diffuse into its surroundings and the colored portion may fade away. For this reason, it might be difficult for the indicator disclosed in the above publication No. 9-299401 to accurately indicate when to replace the diaper.
Similarly, for the absorbent article disclosed in the above publication No. 2003-516185, no attention has been paid to the preventing from bleeding of the color indicator, to make it unnoticeable.
In view of the foregoing, it is an object of the present invention to provide an absorbent article having a structure such that a bled portion of a colored indicator is unnoticeable, thus making it possible to accurately indicate the timing for replacement.